To the Editor: In their randomized controlled trial, Dr de Vos and colleagues1 studied the use of platelet-rich plasma (PRP) injection for the treatment of chronic Achilles tendinopathy. In the study design, an active treatment (eccentric exercises) was used in both the control (saline injection) and intervention (single PRP-injection) groups. It is not clear why the authors chose to do this instead of performing a direct comparison of a recognized treatment (eccentric exercises) against PRP. Given the additional use of eccentric exercises, it does not seem surprising that both groups showed improvement in Victorian Institute of Sports Assessment–Achilles (VISA-A) score. It is also notable that the control group achieved a greater adherence for the eccentric exercises than the PRP-treated group (74.6% vs 70.9%, respectively), which would tend to bias the outcome in favor of the control group.
Creaney L. Platelet-Rich Plasma for Treatment of Achilles Tendinopathy. JAMA. 2010;303(17):1696-1698. doi:10.1001/jama.2010.519